1. Field of the Invention
The present invention relates to a process for producing an anti-soil finishing agent, and more particularly a process for producing an anti-soil finishing agent having a high flash point, a distinguished frozen stability, etc.
2. Related Art
Anti-soil finishing of fabrics is usually carried out by making fabrics hydrophilic or finishing with fluorine-based resins, silicone resins, oil and fat, etc. Above all, finishing with fluorine-based resin is based mainly on anti-soil finishing effect of fluorine on water- and oil-repellency or on a flip-flop mechanism derived by combination with hydrophilic groups, and is now most widely used owing to their properties and easy finishing procedure.
The finishing with the fluorine-based resin is carried out mainly with copolymers of fluoroalkyl group-containing (meth)acrylate esters with hydrophilic group-containing (meth)acrylate esters (e.g. JP-B-52-35033, JP-B-63-474, U.S. Pat. No. 3,574,791, etc.), and the copolymers are generally produced by solution polymerization, where the copolymerization reaction is based on reaction of monomers of mutually contracting properties, i.e. reaction of fluoroalkyl group-containig monomers with hydrophilic group-containing monomers and therefore the solution polymerization reaction is carried out upon appropriate selection of a best solvent for both monomers. Practically, solvents with a low flash point, e.g. alcohols such as ethanol, isopropanol, etc. and ketones such as acetone, methylisobutyl ketone, etc. or mixtures thereof with water are used in most cases (JP-A-53-134786).
Solution polymerization procedure requires no pre-emulsification by a homogenizer, etc. and no complicated polymerization operation, but a high flash point type is desirable from the viewpoints of a risk problem of solvent inflammability, etc. and an ecological problem. One of these problems can be easily solved by using a solvent of high flash point, but the polymerization reaction using such a solvent is not only costly, but also brings about a failure in dispersion when the polymerization reaction solution is diluted with water, resulting in poor stability as another problem.
An object of the present invention is to provide a process for producing an anti-soil finishing agent having not only a high flash point, but also distinguished frozen stability and high temperature stability (storage stability at a temperature of about 40xcx9c50xc2x0 C. higher than room temperature).
The object of the present invention can be attained by producing an anti-soil finishing agent by copolymeriging a fluoroalkyl group-containing monomer with a hydrophilic group-containig monomer in polypropylene glycol having an average molecular weight of not more than about 1,000 or a mixture thereof with a water-soluble organic solvent having a boiling point of not less than 150xc2x0 C. or a flash point of more than 61xc2x0 C.
Generally, fluoroalkyl group-containing (meth)acrylate esters are used as a fluoroalkyl group-containing monomer, where a perfluoroalkyl group Rf having 6, 8, 10 or 12 carbon atoms or a mixture thereof is preferably used as a fluoroalkyl group and specifically include the following compounds, wherein m being 4, 6, 8, 10 or 12, or a mixture thereof:
CH2xe2x95x90CHCOOCH2CH2Rf
CH2xe2x95x90C(CH3)COOCH2CH2Rf
CH2xe2x95x90CHCOOCH2CH(OH)CH2Rf
CH2xe2x95x90C(CHCOOCH2CH(OH)CH2Rf
CH2xe2x95x90CHCOO(CH2) 3C8F17 
CH2xe2x95x90CHCOO(CH2) 4CEF17 
CH2xe2x95x90CHCOOCH2CH2(CF2)mCF(CF3) 2
CH2xe2x95x90C(CH3)COOCH2CH2(CF2)mCF(CF3)2 
CH2xe2x95x90CHCOOCH2CH2N(CH3)SO2C8F17 
CH2xe2x95x90C(CH3) COOCH2CH2N(CH3)SO2C8F17 
CH2xe2x95x90CHCOOCH2CH2N(C2H5)SO2C8F17 
CH2xe2x95x90C(CH3)COOCH2CH2N(C2H5)SO2C8F17 
CH2xe2x95x90CHCOOCH2CH2N(C3H7)SO2C8F17 
CH2xe2x95x90C(CH3)COOCH2CH2N(C4H9)SO2C8F17 
CH2xe2x95x90CHCOOCH2CH2N(C4H9)SO2C8F17 
CH2xe2x95x90C(CH3)COOCH2CH2N(C4H9)SO2C8F17 
Generally, hydrophilic group-containing (meth)acrylate esters are used as a hydrophilic group-containing monomer, and compounds represented by the following general formula are preferably used:
CH2xe2x95x90CRCOO(CH2CH2O)m[CH2CH(CH3)O]nRxe2x80x2
R: Hydrogen atom or methyl group
Rxe2x80x2: Hydrogen atom or lower alkyl group
m: Integer of 1 or more
n: 0 or an integer of 1 or more
m+n:1-60
The fluoroalkyl group-containing monomer and the hydrophilic group-containing monomer are subjected to copolymerization reaction so that the resulting copolymer can have a ratio of the former to the latter of about 30-80 wt. % : about 70-20 wt. %, preferably about 30-60 wt. % : about 70-40 wt. %, total being 100 wt. %. An appropriate monomer ratio of the copolymer can be selected in view of a balance between the lipophilic property and the hydrophilic property of the resulting copolymer.
In addition to the foregoing monomers, other vinyl monomers can be further copolymerized therewith in a proportion of not more than about 30 wt. % to the sum total of the foregoing monomers to modify the copolymer or improve the adhesiveness to fibers. Such vinyl monomers include 3% (meth)acrylate esters having other hydrophobic groups than fluorine, hydrophilic group-containing (meth)acrylate esters having a lower molecular weight than that of the aforementioned hydrophobic group-containing monomers, cationic or anionic (meth)acrylate esters, etc. and specifically include the following compounds:
CH2xe2x95x90CHCOOCH2CH(OH) CH3 
CH2xe2x95x90C(CH3)COOCH2CH(OH)CH3 
CH2xe2x95x90CHCOOCH2CH(OH)CH20H
CH2xe2x95x90C(CH3)COOCH2CH(OH)CH2OH
CH2xe2x95x90CHCOOCH2CH(OH)CH2CH3 
CH2xe2x95x90C(CH8)COOCH2CH(OH)CH2CH3 
CH2xe2x95x90CHCOOCH2CH2CH2CH2OH
CH2xe2x95x90C(CH3)COOCH2CH2CH2CH2OH
CH2xe2x95x90CHCOOCH2CH2OCH3 
CH2xe2x95x90C(CH3)COOCH2CH2OCH3 
CH2xe2x95x90CHCOOCH2CH2OCH2CH3 
CH2xe2x95x90C(CH3)COOCH2CH2OCH2CH3 
CH2xe2x95x90CHCOOCH2CH2OCH2CH2CH2CH3 
CH2xe2x95x90C(CH3)COOCH2CH2OCH2CH2CH2CH3 
CH2xe2x95x90CHCOOC2H4N+(CH3)3Clxe2x88x92
CH2xe2x95x90C(CH3)COOC2H4N+(CH3)Clxe2x88x92
CH2xe2x95x90C(CH3)COOC2H4N30 (CH3)3OSO3CH331 
CH2xe2x95x90C(CH3)COOC2H4N+(C2H5)2HCl31 
CH2xe2x95x90C(CH3)COOC2H4N+(CH3)3Br31 
CH2xe2x95x90C(CH3)COOC2H4N+H(C2H5)2CH3COO31 
CH2xe2x95x90C(CH3)COOCH2CH(OH)CH2N+(C2H5)3Cl31 
The following vinyl compounds can be also likewise used: benzyl (meth)acrylate, cyclohexyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, acrylonitrile, acrylamide, vinyl acetate, styrene, chlorostyrene, chlorobutyl vinyl ether, chloropropyl vinyl ether, chloroethyl vinyl ether, chloromethyl vinyl ether, N-methylol (meth)acrylamide, N-methylol acrylamide butyl ether, N-methylol (meth)acrylamide methyl ether, etc.
The foregoing monomers are subjected to solution polymerization in polypropylene glycol of water-soluble diol type or triol type having an average molecular weight of not more than about 1,000. The polypropylene glycol is used in an amount of about 1-10 times, preferably about 1.5-6 times the total weight of the monomers.
A water-soluble organic solvent having a boiling point of not less than 150xc2x0 C. or a flash point of more than 61xc2x0 C. can be used together with the polypropylene glycol, where the polypropylene glycol is used in an amount of about 0.1-2 times the total weight of the monomer and the water-soluble organic solvent is used in an amount of not more than about 3 times the total weight of the monomers.
The water-soluble organic solvent for use in the present invention includes, e.g. glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, etc., or their acetates, and aprotic polar solvents of low toxicity and high polarity, soluble in most organic solvents, such as N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, etc.
Copolymerization reaction in such a solvent can be carried out by the ordinary solution polymerization procedure.
The anti-soil finishing agent obtained by the solution polymerization procedure is used as an aqueous dispersion upon dilution with water, where the aqueous emulsion desirably has a total content of polypropylene glycol and copolymer (as will be hereinafter referred to as xe2x80x9cmeasurable solid contentxe2x80x9d) of not less than about 20 wt. %, preferably about 20-40 wt. % on the basis of the aqueous dispersion. Below about 20 wt. %, the stability will be lowered in some cases.
In practical anti-soil finishing, the aqueous dispersion is further diluted with water to adjust a copolymer concentration (calculated from the amounts of monomers subjected to the copolymerization reaction) of the resulting diluted aqueous dispersion to about 0.3-7 wt. %, preferably about 0.5-5 wt. %, and used to give finished fabrics an anti-soil property or a soil cleanability.
When a fiber finishing agent usually used in fiber finishing, such as melamine resin, glyoxal resin, triazine-based resin, uronic resin, ethylene-urea-based resin, propylene-urea-based resin, etc. is used together with the anti-soil finishing agent, durability, etc. can be much more improved. It is preferable to use glyoxal resin at a concentration of about 1-10 wt. % or melamine resin at a concentration of about 0.5-1 wt. % in the diluted aqueous dispersion together with their curing catalyst.
Anti-soil finishing is carried out by any fabric-penetrating procedure such as a pad process, a dip dyeing process, a spray process, a coating process, etc. For example, a pad process applicable to cotton fabrics is carried out by padding in a pickup ratio of about 70-100%, drying at about 70xc2x0-160xc2x0 C. for about 1-3 minutes and curing at about 130xc2x0-180xc2x0 C., which must be higher than the drying temperature used, for about 1.5-2 minutes. For other fabrics than the cotton fabrics, finishing conditions depend on fabric species.
The present anti-soil finishing agent has a high flash point and the aqueous dispersion prepared therefrom has distinguished frozen stability, high temperature stability, etc. as well as the high flash point, and particularly shows high levels of anti-soil property, soil cleanability, recontamination-preventive property, washing durability, etc. in case of synthetic fibers such as polyester, polyamide (nylon) fibers, etc. The present anti-soil finishing agent having such characteristics are distinguished not only in the antisoil finishability, but also in safety, as compared with the conventional anti-soil finishing agents obtained by polymerization in a solvent of low flash point, and thus is effectively easier in handling such as storage, etc.